help me to do chat program

Question

hi i am newbie to this i want to do chat program in asp.net for my company.my need is if i specify that remote ipaddress in my textbox and press button thet invitation has to go to that remote system using ipaddress and one popup mas has to come for that remote system that has to indicate "this fellow from this ipaddress inviting u for chat".then they both can chat this is my need, can u provide coding to do this chat pleeeeeeeeeeeeese, i m going to use this in a LAN